Paper makers&#39; felt



J. P. KOESTER PAPER MAKERS Sept. 17, 1968 FELT Original Filed Dec. 7,1964 INVENTOR JOHN P. KOESTER United States Patent 3,401,467 PAPERMAKERS FELT John P. Koester, Piqua, Ohio, assignor to The Orr Felt &Blanket Company, Piqua, Ohio, a corporation of Ohio Continuation ofapplication Ser. No. 416,273,Dec. 7, 1964. This application June 5,1967, Ser. No. 643,527 4 Claims. (Cl. 34-95) ABSTRACT OF THE DISCLOSUREA papermakers felt and method of making the same is disclosed in which awoven base material is woven with soluble filler yarns formed of calciumalginate and which are removed after battings have been needled into thebase material to form a finished felt substantially free of crosswisestructure.

This application is a continuation of application Ser. No. 416,273,filed Dec. 7, 1964, and now abandoned, assigned to the same assignee asthis application.

The surface characteristics of a paper makers felt has a direct bearingupon the finish and quality of paper formed thereon. It has beensuggested that if a felt were made with warp yarns only, and with batsof fibers needled into these yarns, a finished felt would be formedwhich has no filler yarns and therefore has no cross over points orknuckles to mark on finished paper. It has been considered that such afillerless felt would more nearly approach the ideal paper makers feltto the extent that it would emboss fewer or less prominent felt marks onthe Wet paper sheet. Although it-is well known that the stock furnishedto the paper making machine has an effect on the degree of marking, sucha felt would allow the paper maker a wider latitude in the selection andpreparation of the stock.

It has further been thought that a felt which has no filler yarns wouldexhibit improved drainage characteristics since there would be a lesstortuous path for the water to flow through the felt. First, such a feltwould offer less resistance to water fiow since the water would not meetthe high resistance areas of the filling yarn. Second, such a felt couldbe thinner by reason of the absence of the filler and because of thisthickness, the water could flow through more easily.

A fillerless felt would also, at least in some instances, have improvedwear resistance. Many conventional felts tend to wear at the cross overpoints of the warp and filling yarns due to the high pressures at thesepoints. Obviously, this would not occur in a felt which has no filleryarns.

Suggestions have been made for manufacturing a felt without a filleryarn. Such suggestions presuppose an endless array of warp yarns whichare somehow formed, and held in proper spatial side-by-siderelationship, while a non-woven batting is needled into the array. Bothadjacent loop'placement and helix winding the warp yarns have beensuggested. However, no practical warp forming machine has been describedfor this purpose. Therefore, no practical or commercial method has beensuggested by which a fillerless belt or base may be formed and handledin the lengths and widths which are required for paper making machines.There would be a difiicult problem in forming a parallel array of warpyarns without filler at the proper length and width, and in holding themwithout twisting, or crossing over of adjacent yarns, and maintainingproper tension throughout to permit subsequent handling .and needling.The filler material in a conventional woven felt performs an invaluableservice in permitting the initial forming and handling of the felt,conventional splicing into an endless belt of desired length,

and maintenance of the relationship of the warp yarns prior to andduring the needling operation.

The method of this invention and the felts produced thereby include theweaving of a base material of the desired warp yarns with a filler yarnwhich is removable in one of the finishing operations of the felt afterthe felt has been needled. In the preferred embodiment of thisinvention, a woven base material is formed using the desired warp yarnsin a weave including a filler yarn, at least a substantial portion ofwhich is selectively soluble or removable, as by a solution or liquidwhich is harmless to the warp yarns and batting. Such a filler yarn maybe formed of continuous filament calcium or sodium alginate. It may alsobe formed of slit and twisted soluble film material such as a polyvinylalcohol. The woven base material may then be handled in the conventionalmanner. Such a base material may then be needled to apply one or morebats of non-woven fibers into the base material, interlocking the samewith the warp yarns and providing the desired surface characteristicsand resistance to widening. Subsequent to such needling, the felt isde-woven by the removal of the filler material in a suit-able solvent. Ade-woven and fillerless felt is accordingly formed which may then besubjected to any other desired finishing operations such as washing,fulling, heat treating, and the like.

It is accordingly an important object of this invention to provide anendless paper makers felt which has been de-woven after needling toremove part, if not all, of the filling yarns.

A further object of this invention is to provide an improved process formaking a fillerless endless paper makers felt.

A still further object of this invention is the provision of a method ofmanufacturing an endless paper makers felt which, when finished, hasonly a w-arp yarn system combined with needled, non-woven battings.

A still further object of this invention is the provision of a methodfor making an endless paper makers felt by initially supporting the warpyarn structure using a woven and soluble filler material, such ascalcium .algin-ate, and removing the same after it has served itspurpose, and the provisions of a product manufactured by such process.

A still further object of this invention is the provision of a de-wovenendless paper makers felt which has had the filler yarns removed andwhich has been provided with an arrangement of needled batting materialto provide sufficient crosswise strength or resistance to widening foroperation on a paper making machine in the absence of such filler yarns.

A further object of this invention is the provision of an article ofmanufacture which is useful as an intermediate product in themanufacture of a paper makers felt which includes a woven base materialof a plurality of warp yarns which are held in parallel array by afiller formed at least in part of calcium alginate fibers or othereasily and selectively removable fibers as by solvents or otherwise andwhich woven material is joined as by weaving as a tube or by splicing atits opposite ends to form continuous warp yarns in an endless belt.

These and other objects and advantages of the invention will be apparentfrom the following description, the accompanying drawings and theappended claims.

In the drawings FIG. 1 is a perspective view of a portion of an endlesspaper makers felt showing the application of a non-woven batting on aneedling loom to a base material formed as an endless belt made inaccordance with this invention;

FIG. 2 is a fragmentary perspective of the belt of FIG. 1, partiallybroken away, of one of the products of this invention showing the feltafter needling and before the removal of the filler yarns;

FIG. 3 is a perspective view, partially broken away,

similar to FIG. 2 following the removal of the filler yarns; and

FIG. 4 is a fragmentary perspective view, partially broken away, similarto FIG. 3, showing a slightly different form of the invention.

Referring to the drawings which illustrate a preferred embodiment of theinvention, a woven base material made in accordance with this inventionis illustrated generally at 10 in FIG. 1. This base material comprisesconventional warp yarns 12 which are more clearly seen in FIGS. 2 and 3.The warp yarns 12 are chosen to provide the desired tensional strengthand weight lengthwise of the belt, and are further chosen with regard tothe desired material, thickness and weight of the same as is known inthe art. Woven into the base 12, such as by a conventional loom, arefiller yarns 14. The filler 14 is preferably formed of a selectivelysoluble material or a material which may be removed by subjecting thefelt to a suitable solution harmless to the remaining fibers.Preferably, the filler 14 is formed of filament type calcium alginatewhich is soluble in soda ash or sequestering solutions which are hamlessto the other materials in the finished felt. However, the invention isnot intended to be limited thereto as other suitably selectivelyremovable fibers, yarns or slit and twisted films may be used. Also,sodium alginate filaments may be used which are water-soluble.

Preferably, only so much of the filler material 14 is used as necessaryto permit ease of handling of the Woven base 10. Accordingly, arelatively light filler 14 may be satisfactory for the purpose ofpermitting the ease of handling, the joining together of the ends of thebase material 10 to form an endless belt (FIG. 1) and the preparationand handling of the same on a needling loom.

It is also within the scope of this invention to blend the solublefiller yarns or fibers 14 with a small amount of insoluble yarns, suchas, for instance, a blend of 75% calcium alginate staple with 25%insoluble fibers such as wool or synthetic. When the calcium alginate isremoved, residual fibers 14' (FIG. 4) will be retained to provide asoft, strong, and substantially non-marking crosswise structure whichwill assist in producing a desired crosswise strength or resistance towidening. It is clear that in the absence of the major portion ofsoluble filling fiber it would be difficult, if not impossible, to weavein such a small proportion of non-soluble and substantially nonmarkingcrosswise structure of this type.

The base material 10 may be woven in the endless or tubular form inwhich the warp 12 is actually the filler in the loom. However, thistechnique is limited both by the size of the loom and the texturedensity and size of the warp yarns. Accordingly, when longer finishedlengths and higher densities are required, the base material 10 may bewoven in the conventional manner and formed in an endless belt bysplicing the ends together, also in a conventional manner. This resultsin the individual warp yarns 12 being joined by overlapping at oppositeends so that, in effect, the warp runs in substantially unbrokencontinuity. Thus, the use of a removable r fugitive filler 14 permits awoven base material to be handled by Wholly conventional techniques.

Following the conventional splicing or tubular weaving of the basematerials at the desired length, the resulting belt is placed on aconventional needling machine. To this base material there is needlednon-woven batting material such as the bats 15 and 16 shown in FIG. 1 bya needle loom 17 to surfaces of the woven base 10. One or more of suchbats 15 and 16 may be applied to one face and preferably both the outerand inner faces, as necessary to provide a desired finishedcharacteristic and resistance to widening in the finished felt. It hasbeen found that first bats 15 and 16 of synthetic fibers needledrespectively into both the face and the black of the fabric 10, followedby a second bat 18 (FIG. 4) of W001- en fibers needled into the face orouter surface, and subsequently fulled, provides a superior resistanceto widening in the cross-machine direction.

In FIG. 2 there is shown a fragment of the intermediate product of thisinvention prior to the removal of the filler 14. The bat 15 has beenneedled to the pper or outer surface which may actually comprise one ormore individual bats of synthetic or woolen material and may preferablybe formed with an under layer of synthetic with a woolen face bat 18applied in separate needling steps. A similar needling bat or layer 16has been needled into the inner or bottom surface of the woven base 10with the result that the fibers thereof and of the bat 15 are intimatelyinterlocked and mingled one with the other and with the warp yarns 12and compacted tightly against the base material.

The relationship of the warp yarns is now fixed and held by the needlebats l5 and 16. The filler yarns 14 have now served their purpose andmay be removed. If these yarns are formed of calcium alginate fibers,they may be removed by washing the felt in a suitable sequesterene agentor solvent. For instance, the fibers may be removed in an alkalinesolution of soda ash (Na CO and common salt (NaCl). However, wherefibers in the remaining felt are not resistant to alkaline conditions, asolvent may be employed which uses sodium hexametaphosphate with a smallamount of detergent-dispersant and common salt added.

It has been found that after ten minutes of Washing the felt in suchsolutions, preferably at lukewarm temperatures, the calcium alginatefiller 14 is completely removed, as shown in FIG. 3. Preferably, thefelt is then rinsed, and prepared for any other wet finishingoperations, such as fulling and the like. The felt may then be dryfinished in the normal manner. The resulting product is one which hasbeen dc-woven by the removal of the filler 14, leaving only the warpyarns 12 in fixed predetermined relationship, locked in place within theneedled battings applied to the outer and inner surfaces thereof. Theparellel relationship of the warp yarns has easily and conveniently beenmainted during the criticial forming steps. The filler 14 has madepossible the conventional handling of the base material including theimportant joining or splicing step in which the woven material is formedinto an endless belt, and has further maintained the desiredrelationship during the needling operation.

As an example, and in no way intended to limit the scope of theinvention as defined in the appended claims, a felt was made to operateat 49 feet at the finished length, by 40 inches wide. A wrap yarn wasselected which. weighed 250 grains per yards. A filler yarn 14 of purecalcium alginate filament material was used with a weight of grains per100 yards. The filler yarn was of twoply construction and was a balancedyarn. The felt was woven in a conventional loom with 26 ends per inchand 22 picks.

After the felt base material was woven the ends thereof were joined bysplicing in the conventional manner. The felt was then applied to aneedle loom using 32 gauge needles. First, a ounce per square footpolypropylene non-woven fiber was anchored to the back of the basematerial by needling one round at a rate of 400 strokes per minute usinginch peneration and inch advancement.

The felt was then turned so that a batting could be applied to the face.This face batting also consisted of of an ounce per square foot ofpolypropylene and'was anchored to the face using the same stroke perminute, penetration and advancement indicated above.

Next, a finishing layer of wool batting was needled to the face. Thisconsisted of one-half ounce per square foot of wool fibers and wasneedled in at the same rate, penetration and advancement describedabove.

The felt was then removed from the needling machine and washed in 100gallons of solution at 120 P. which contained the following:

Gallons of Calgon solution (sodium hexametaphos- The felt was washed inthis solution for twenty minutes in a conventional felt washing machinerunning at relatively low speed. It was then rinsed in warm water in thesame machine for twenty minutes. This procedure completely removed alltraces of the filler 14. The felt was then acid fulle-d until it hadlost approximately one-half of its woven width, and wet and dry finishedin the normal manner.

Laboratory tests have indicated that the de-woven structure made inaccordance with the above example exhibited excellent stability. Ameasurement of stability is the ratio of the width of the felt at twotimes the running load to its width in a completely relaxed condition.Since there are no filler fibers or yarns remaining in the structurethere is little width reaction. This felt had a ratio of 0.986 to one,which may be compared to approximately 0.9 to one for a normal felt.This relatively high stability and resistance to narrowing under tensionindicates that the felt, in use, has very little tendency to become morenarrow when tensioned on a paper machine.

In use, the felt exhibited superior stability both as to width and as tolength. The felt went on a paper machine at 42 inches wide and variedless than of an inch in width when loaded between 110 pounds per linearinch to 340 pounds per linear inch at the press section. This widthstability can be attributed to the absence of the filler 14 resultin inminimum width reaction.

The same felt had only a four inch variation in length between runningloose and taut on the machine. In the loose condition, the felt wasfifty feet, eight inches long, and when it was running taut the felt was51 feet long. This stability as to length may be attributed to the factthat no crimp remained in the warp after the filler was removed.

The felt produced paper of superior finish with an almost completeabsence of any characteristic marking on the paper surface. The feltalso has improved wear capabilities in that it has no cross over pointsor knuckles and, accordingly, no hard spots to accelerate wear.

The above felt made according to this invention also exhibited superiorcharacteristics with regard to shedding. All fibrous products will losesome fiber as they wear. However, many of the sheddable fibers areremoved from the felts of this invention during the processing of thefelt, and particularly during fulling. This shedding is primarilyrestricted to the short fibers in the felt which would be of noadvantage to the finished felt and which are probably produced by thecutting action of the needles during the needling steps. The sheddablefibers are more easily removed due to the absence of the filling yarnsand provides a finished felt which is more resistant to shedding in use.

It is accordingly seen that this invention provides a practical methodof making fillerless endless felts on a commercial basis and a superiorpaper makers felt.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. A fillerless papermakers felt for producing paper of superior finish,free of knuckle and crossover marks, and having superior dimensionalstability, drainage and wearing qualities, comprisin a plurality ofindividual 6 warp yarns arranged in a generally parallel array of saidyarns forming a base material, with said base material being formed inan endless belt with said individual warp yarns running lengthwise ofsaid belt in generally straight parallel lines free of crimps andcrossovers, battings of non-woven essentially synthetic fibers needledinto the face and back surfaces of said base material forming a cushionfor said yarns and interlocking said yarns thus resisting widening ofsaid base material when said felt is applied to a papermakers machine,and a layer consisting essentially of wool fibers needled into a facesurface of one of said non-woven battings.

2. A papermakers felt for producing paper of superior finish,essentially free of knuckle and crossover marks, and having superiordimensional stability, drainage and wearing characteristics, comprisinga plurality of warp yarns arranged in a generally parallel array of saidyarns forming a base material, and being formed in an endless belt withsaid warp yarns running lengthwise of said belt in generally straightlines substantially free of crimps and crossovers, a relatively lightarray of substantially nonmarking insoluble residual filler fibers wovencrosswise with said warp yarns forming a soft and non-marking crosswisestructure contributing to the crosswise strength of said felt and beingtoo limited in strength for weaving alone into said warp yarns, andbattings of non-woven fibers needled into the face and back surface ofsaid base material forming a cushion for said yarns and interlockingsaid yarns thus resisting widening of said base material when said feltis applied to a papermakers machine.

3. A product useful in making a papermakers felt, comprising a Wovenbase material including a plurality of warp yarns extending lengthwiseof said base material and,held in a generally parallel array by arelatively light filler in which the essential element is a selectivelysoluble fiber, such as calcium alginate, sodium alginate, polyvinylalcohol, or the like, with said filler being woven into said arraytransversely of the direction of said warp yarns, and battings ofnon-woven fibers being intimately comingled with said base material andcompacted tightly against each surface of said base material forming atleast one layer of non-woven fibers on each side of said base materialcushioning said base material and providing suflicient crosswisestrength to said base material when said felt is used on a paper machinewith said soluble filler fibers removed.

4. A product useful in making a papermakers felt, comprising a wovenbase material including a plurality of warp yarns extending lengthwiseof said base material and held in a generally parallel array by a fillerof a selectively soluble fiber, such as calcium alginate, sodiumalginate, polyvinyl alcohol, or the like, combined with a relativelysmall amount of insoluble fibers, said filler being woven into saidarray transversely of the direction of said warp yarns, and battings ofnon-woven fibers intimately comingled with said base material andcompacted tightly against each surface of said base material forming atleast one layer of non-woven fibers on each side of said base materialcushioning said base material and combining with said insoluble fillerfibers to provide suflicient crosswise strength to said base materialwhen said felt is used on a paper machine with said selectively solublefiller fibers removed.

References Cited UNITED STATES PATENTS 2,898,665 8/1959 Salem et al28-76 3,059,312 10/1962 Jamieson 161-154 XR 3,097,413 7/1963 Draper34-95 FREDERICK L. MATTESON, JR., Primary Examiner. A. D. HERRMANN,Assistant Examiner.

